An investigation by the BBC has found that dozens of videos advocating fake cancer cures on YouTube, some with hundreds of thousands of views, were being monetized by the platform with ads.
Researchers at BBC Monitoring surveyed YouTube across ten languages: English, Portuguese, Russian, Arabic, Persian, Hindi, German, Ukrainian, French, and Italian.
They found more than 80 videos promoting bogus cancer cures, 47 of which were accompanied by ads. Some of the ads were for established brands including Samsung, Heinz, Grammarly, and Clinique.
The videos endorsed consuming substances like juice, turmeric, baking soda, and even donkey's milk as ways to prevent or even cure cancer.
The video the BBC found promoting donkey milk had over 446,000 views at time of writing.
YouTube announced in a blog post in January that it would crack down on "borderline content and content that could misinform users in harmful ways." It described the enforcement as a "gradual change" that would only apply to videos from the US to begin with.
Once the BBC informed advertisers about their campaigns running alongside the videos, some distanced themselves. Kraft Heinz and Grammarly said they had taken steps to block the channels responsible.
YouTube demonetized 70 of the videos after being contacted by the BBC, a spokesman told Business Insider.
The spokesman said: "Misinformation is a difficult challenge, and we have taken a number of steps to address this including showing more authoritative content on medical issues, showing information panels with credible sources, and removing ads from videos that promote harmful health claims.
"Our systems are not perfect but currently, the majority of the searches about cancer cures are pointing users to authoritative sources. We're constantly making improvements, and we remain committed to progress in this space."
Business Insider's Tom Porter found a network of videos pushing an autism "cure" called Miracle Mineral Solution (MMS), which contains industrial bleach.